What do you think a good daily dose of vitamin D is?

A. Dear Nancy, Vitamin D is incredibly important to virtually every cellular process within our body. When our skin is exposed to sunlight, there are certain cells that undergo changes and convert a special kind of cholesterol into usable, vitamin D. There are many factors that can impact how efficient this process is: including age, latitude, cholesterol status, ethnicity, and many others.

By age 65, changes to our skin – regardless of color – reduce our ability to produce vitamin D by up to 60%. Low levels of vitamin D at age 65 mean you are twice as likely to experience mental decline. In one clinical study, adult volunteers with even moderate vitamin D deficiencies had a 53% increased risk of dementia and a 69% increased risk for Alzheimer’s disease. Severe vitamin D deficiencies showed a 125% risk of dementia and a 122% risk of Alzheimer’s.

While the recent increase of the RDA (recommended daily allowance) for vitamin D is promising, I think the level may still be too low for most people to receive many of the therapeutic benefits of vitamin D. This is especially important for the people living in areas of the world where receiving vitamin D from the sun may not be available year-round, such as North Dakota.

Personally, I think 2000-5000 IU of vitamin D per day is a much better amount for maintenance of good health and treatment of certain health conditions. I prefer to use vitamin D3, as cholecalciferol, because it is in the human form. There is also vitamin D2, as ergocalciferol, but this form is much less effective at raising vitamin D levels.